In the comparatively short time I have had my .177 S400 Classic I have had quite few problems with the breech seal coming out or not sealing properly. As an experiment, I have fitted a BS 008 0-ring which is a bit bigger and fatter at 4.47 x 1.78 mm than the normal 4.5 x 1.5 mm. It fitted easily enough, is still in place after about 1000 shots and the pellets feed in perfectly despite the slightly smaller hole. It increased the speed of an AADF 8.4 grain pellet by 6 to 8 fps, and reduced the average shot-to-shot variance of a 100 pellet string - which I find a more useful measure of consistency than SD for an unregulated gun - from 2.8 to 1.7 fps. The effect on my HFT 500 was much the same.

I'm not sure how much this matters in practice, but the theoretical improvement is pretty clear. Anyone else tried this? Am I just reinventing a well known wheel?

Alan

Edit: I have changed the velocity figures as I was reading the wrong spreadsheet, sorry. However the overall picture is still the same.

Just looking at them, I think they are the standard, metric size. The other difference is that the Bagnall and Kirkwood ones are nearly 5 quid for 2, the BS 008's are just over 5 quid for 100 (if you want that many!)

Just looking at them, I think they are the standard, metric size. The other difference is that the Bagnall and Kirkwood ones are nearly 5 quid for 2, the BS 008's are just over 5 quid for 100 (if you want that many!)